The invention relates to a method for switching between desired value filters of a machine control system for a drive means of a machine during operation. The invention also relates to a program, to a control unit of a machine and to a machine of this kind.
From EP 0 477 412 A1 a filtering method is known for a machine control system, in which digital signals are smoothed using filters. The filters, which are to be switched between, have different filter lengths. The path difference between the path specified by the desired values and the reduced path covered owing to the filter is determined. During switching, the path deviation along the direction of movement is minimized by mathematical modification of a feedback loop to the signal input.
EP 0 135 024 B1 discloses a transmission arrangement for audio signals, which have two signal paths, with a digital transmission element being arranged in each signal path. Each transmission element has a coefficient set relating to its configuration. Provided between the signal paths is a discriminator, which is supplied with the output signals of the two transmission elements. The mathematical sign of a difference between the output signals of the two transmission elements is detected and, in the case of a change of sign, a switching, signal is given for the transmission elements.
One drawback of known options for switching between different filters is that there is a considerable risk of a step-like, in other words discontinuous, transition in the case of the desired values of the output signals with which the drives of a machine are controlled. A sufficiently smooth transition from one filter to another, as is necessary for example for precision applications, typically requires a stoppage of the respective machine axis. Furthermore, switching methods, in which there is a reduced risk of a step-like transition of output signals, require high computing power. There is a need for a filter switching method which overcomes the drawbacks from the prior art, which reliably enables smooth switching between different filters during a machine movement, and which can be implemented with low demands in terms of computing power.